1. Field of the Invention
The present invention relates to a spray apparatus and more particularly to an automated apparatus for spraying herbicides on roadsides and other right-of-ways. The sprayer is mounted to a vehicle and is controlled by the operator of the vehicle.
2. Description of the Related Art
A right-of-way sprayer typically includes a tank for storing the herbicide and a dilution source, normally water, also stored in a tank. The herbicide and dilution sources are connected to a water pump where a mix occurs. The mix is then fed into a manifold controlled by solenoids that allow the operator to direct the flow of the mix. After traveling through the manifold, the mixture is fed through a series of hoses to individual nozzles, which mount on the ends of the plastic hoses. The nozzles are then mounted on a common platform called a spray head. The spray head can be nutated by any suitable means such as an electric vibrator to create droplet separation at the nozzles.
The spray head, as well as the nozzles, may be remotely controlled by a vehicle operator, or a weed sensor may be utilized to determine the presence of vegetation. The vehicle operator can change the position of the spray head through the use of a power unit, such as an electric, air, or hydraulic cylinder to change the inclination of the spray head as the cylinder extends or contracts. In addition, individual swaths or nozzles can be controlled by the operator using a single switch, or any combination of switches to achieve a desired spray swath. The switches control the delivery of power to solenoids connected to the manifold. The ability to control the delivery of product to the nozzles using the switch allows the operator to provide a number of different swath patterns according to the type of application preferred. Also, a roadside sprayer may include a means of sensing vehicle speed, such as a ground based radar, or global positioning system (GPS), to help the operator to regulate the speed of the vehicle and the application rate of chemical.
Current right-of-way sprayers provide several advantages. The sprayers allow for a plurality of individual nozzles to cover swaths at different distances from the vehicle. Also, the nutation speed of the spray head may be adjustable to compensate for wind and to minimize drift, thereby achieving more uniform spray coverage. The spray head can also be positioned at different angles to produce the desired swaths.
However, in current right-of-way sprayers, the nozzles are not rigidly mounted on the spray head. Instead, the nozzles are threaded into ninety-degree elbows. The elbows are threaded into a series of common manifolds holding sets of spray nozzles. Hoses carry fluid from a remote system of solenoids to the manifolds holding the sets of spray nozzles. This lack of a rigid mounting system for the nozzles can cause several problems. Illustratively, the lack of rigid mounting for the nozzles can create a disproportionate level of nutation in the nozzles. The lack of uniformity in the level of nozzle nutation creates a varying level of droplet sizes among nozzles designed to nutate at the same rate, thereby affecting swath coverage and the saturation level of the herbicide.
Additionally, nutation of the spray head forces the elbows to rotate with respect to the manifolds, thereby moving the nozzles out of position. In this instance, a spray stream emitted from a nozzle overlaps an adjacent nozzle. In this situation, the chemical is applied unevenly, and the reoriented nozzle produces a spray pattern that lacks uniformity.
Also, as the ends of the nozzles are not rigidly attached to a rigid structure, the nozzles may point and direct spray to unintended locations producing undesirable swath coverage. The lack of a rigid mounting system also increases the potential of causing nozzles to vibrate loose from their mounting points.
Still further, the remotely located solenoids create issues with residual product disposed within fluid circuits located beyond the flow control shut-offs. Illustratively, remotely located flow control units leave large quantities of product disposed within the fluid system after a spray. The residual fluid remains in the pressurized hoses, and then seeps out of the system as the hoses contract due to the pressure loss. The residual fluid may also drip out of the system during a change in the orientation of the system components, such as during a retraction, thereby delivering unintended drippage, possibly on desirable turf.
Still, yet further, the prior art utilizes a spray head including high-weight components. As such, a motion inducer is forced to work in a high working load range, thereby increasing the rate of motor and bearing failures.
Accordingly, a right-of-way sprayer that produces more uniform motion among nozzles, and prevents moving nozzles from pointing in unintended directions, would enable more consistent and accurate swath coverage. Moreover, a fixed nozzle mounting system would reduce nozzle vibration, ensuring that nozzles remain in their mounting points.